| FA | Field artillery |
| Fourier analysis |
| FAA | Federal Aviation Administration (USA) |
| FAC | Forward air control |
| fac | Facility |
| FACP | Forward air control post |
| FADEC | Full authority digital engine control |
| FAF | Final approach fix |
| FAhd | Full ahead |
| FAI | Final acceptance inspection |
| FAM | Fast-access memory |
| FAMS | Family of anti-missile systems |
| FANS | Future air navigation system (ICAO) |
| FAO | Food and Agriculture Organisation (UN) |
| FAQ | Frequently asked question |
| FAR | Federal acquisition regulation |
| Federal airworthiness requirement (USA) |
| Federal aviation regulation |
| FARP | Fully automated radar plotting |
| FAS | Fuelling at sea |
| Future attack submarine |
| FASC | Forward air support centre |
| FAstn | Full astern |
| FAT | File allocation table |
| fax | Facsimile |
| FBA | Fighter-bomber attack |
| fbd | Freeboard |
| FBL | Fly by light |
| FBMS | Future battlefield management system |
| FBS | Fighter-bomber strike |
| FBW | Fly by wire |
| FC | Fighter controller |
| Fire control |
| FCC | Fire control computer |
| FCE | Fire control equipment |
| FCO | Foreign and Commonwealth Office |
| FCPC | Flight control primary computer |
| FCS | Fire control system |
| Flight control system |
| FCSC | Flight control secondary computer |
| FCZ | Forward combat zone |
| FD | Flight director |
| FDC | Fire direction centre |
| FDDI | Fibre-distributed data interface |
| FDEP | Flight data entry position |
| Flight data entry printer |
| FDI | Flight data interchange |
| FDIC | Flight data information computer |
| FDM | Frequency division multiplex (radio) |
| FDPS | Flight data processing system |
| FDR | Flight data recorder |
| FDS | Field dressing station |
| FE | Flight engineer |
| Flight envelope |
| FEA | Finite element analysis |
| FEBA | Forward edge of battle area |
| FEC | Forward error correction |
| FED | Field emission display |
| FEK | Frequency exchange keying (telegraphy) |
| FEP | Fluoroethylene polymer |
| FES | Field-emission spectroscopy |
| FET | Field effect transistor |
| FEZ | Fighter engagement zone |
| FFA | Fire-fighting appliance |
| FFAR | Folding fin aircraft rocket |
| FFO | Furnace fuel oil |
| FFOP | Fault-free operating period |
| FFR | Fitted for radar |
| Fitted for radio |
| Free-flight rocket |
| FFS | Full flight simulator |
| FFSS | Future fighting soldier system |
| FFT | Fast Fourier transform |
| FG | Field gun |
| Foreign-going |
| FGA | Fighter ground attack |
| FGL | Force generation level |
| FGS | Flight guidance system |
| FH | Field howitzer |
| Frequency hopping |
| FIBUA | Fighting in built-up areas |
| FIC | Flight information centre |
| FICS | Fully integrated communications system |
| FICV | Future infantry combat vehicle |
| FIFO | First in, first out |
| FIM | Fault isolation manual |
| FIMA | Future international military airlifter |
| FIR | Far infra-red |
| Flight information region |
| FIS | Flight information service |
| FIST | Future integrated soldier technology |
| FITOW | Further improved tube-launched optically tracked wire-guided (missile) |
| FL | Flight level |
| FLA | Future large aircraft |
| FLET | Forward line of enemy troops |
| FLIR | Forward-looking infra-red |
| flop | Floating point operation (computer) |
| flops | Floating point operations per second (computer) |
| FLOT | Forward line of own troops |
| FLPT | Fork lift pallet trailer |
| flt | Flight |
| FM | Field maintenance |
| Frequency modulation |
| fm | Fathom (1.830 m = 6 ft) |
| FMA | Flight mode annunciator |
| Forward maintenance area |
| FMBT | Future main battle tank |
| FMC | Federal Maritime Commission (USA) |
| Flight management computer |
| FMCS | Flight management computer system |
| FMDB | Final mains distribution board |
| FMDZ | Forward missile deployment zone |
| FMEA | Failure modes and effects analysis |
| FMECA | Failure modes, effects and criticality analysis |
| FMGS | Flight management guidance system |
| fMRI | Functional magnetic resonance imaging |
| FMS | Flexible manufacturing system |
| Flight management system |
| Foreign military sales |
| FNPT | Flight navigation and procedures trainer |
| FO | First officer |
| Flag officer |
| FOAM | Forecasting ocean atmospheric model |
| FOB | Forward operating base |
| Free on board |
| FOBS | Fractional orbital bombardment system |
| FOC | Flag of convenience |
| Full operational capability |
| FOD | Foreign object damage |
| FOFA | Follow-on forces attack |
| FOL | Forward operating location |
| FOPS | Falling object protection system |
| Fortran | Formula translation (computer) |
| FOSDIC | Film optical sending device for input to computers |
| FOV | Field of view |
| FP | Flash point |
| Flight plan |
| FPB | Fast patrol boat |
| FPC | Floating point calculation |
| FPDB | Flight plan data base |
| FPDP | Flight plan data processor |
| FPGA | Field-programmable gate array (computer) |
| FPP | Fixed-pitch propeller |
| FPPC | Flight plan process cell |
| FPPS | Flight plan processing system |
| FPRS | Flight plan reception section |
| FPS | Flight progress strip |
| Floating production system (oil) |
| fps | Feet per second |
| see ft/s |
| FPSO | Floating production, storage and offloading (structure or vessel) |
| FPV | Fisheries patrol vessel |
| FQR | Final qualification review |
| FR | Flight rules |
| freq | Frequency |
| FRH | Flameless ration heater |
| FRP | Fibre-reinforced plastics |
| FRS | Fault reporting system |
| FRT | Forward repair team |
| FRV | Fisheries research vessel |
| FS | Flight safety |
| Full scale |
| FSA | Final site acceptance |
| FSC | Forward scatter |
| FSCC | Fire support co-ordination centre |
| FSCL | Fire support co-ordination line |
| FSD | Full-scale deflection |
| FSK | Frequency shift keying (telegraphy) |
| FSM | Frequency shift modulation |
| FSP | Flight strip printer |
| FSS | Forward scatter system |
| Frequency-selective surface sheeting |
| FSTA | Future strategic tanker aircraft |
| FStS | Forward storage site |
| FSU | Floating storage unit |
| FSW | Forward-swept wing |
| FSWR | Flexible steel wire rope |
| FT | Fourier transform |
| ft | Foot (0.305 m) |
| ft/min | Feet per minute |
| ft/s | Feet per second |
| ft/sec | Feet per second |
| FTD | Flight training device |
| FTIR | Fourier transform infra-red (spectroscopy) |
| FTL | Flight time limitation |
| FTP | File transfer protocol |
| Final technical proposal |
| FTS | Fixed telecommunications system |
| FTTCS | Future tactical trunk communications system |
| FUP | Forming up place |
| FW | Fresh water |
| FWC | Fault warning computer |
| fwd | Forward |
| FWL | Foil-borne water line |
| FY | Financial (or fiscal) year |
